It is known to provide automobile wheels comprising roll-formed steel rims and steel hub-spoke castings which are pressfitted and welded together or comprising such steel rims and aluminum castings which are pressfitted together and locked as by dimpling the rims into peripheral depressions in the castings or by providing steel plugs in radial holes in the castings welded to the inside diameters of the rims. For examples of automobile wheels of the character indicated, reference may be had to the U.S. Pat. Nos. 3,484,137, 3,635,529, and No. 3,807,805.
In the manufacture of automobile wheel rims of the character indicated, strip steel stock is roll-formed to rim cross-section and into circular form followed by welding together of the ends and pressfitting the rim around the machined outside diameter of the casting. Accordingly, in a roll-formed steel rim, it is not possible to obtain optimum metal distribution as required to best withstand the stresses and strains imposed on the finished wheel in use. Moreover, a roll-formed steel rim is weaker in some directions than in others. Furthermore, the roll-forming of the steel strip to the desired rim cross-section entails relatively sharp angle bending of the strip so as to impose severe tensile stresses on the outside of the angles and severe compressive stresses on the inside of the angles.
Aside from the foregoing, in some known automobile wheels having roll-formed steel rims and cast aluminum hub and spoke units, the latter have steel inserts providing tabs for welding to the steel rims.